The object of this invention is an automatic servo-controlled valve with high speed opening for the outlet of gas.
It is known that in industrial plants in general, and nuclear plants in particular, there are premises where a sudden and uncontrollable increase of pressure may take place, because of fire, explosions, gas or steam escape, and the like.
To prevent such pressure increases it is necessary to provide for quick breaking diaphragms so as to allow the gas to escape.
The main disadvantage of such quick-breaking diaphragms is that, after their operation, i.e. after their breakage, they must be substituted: hence they can be used only once. Apart from the economic aspect brought about by the diaphragm substitution, it is clear that they can be calibrated on a statistical basis only, by causing the breakage of some of the diaphragms that are to be installed in the plant concerned.
Moreover, if very large escape areas are required for very low differential operating pressures, and even though special materials are used, a limit of incompatibility is soon reached between the high sensitivity and the stability requirements (acceptability of the risk of improper diaphragm breakage).